Wear parts, buckets and loading platforms for mining or construction machines are subjected to heavy wear from abrasive material during the process of loading and unloading.
In order to increase the wear-resistance of loading buckets, bucket teeth with considerable dimensions are used which are fastened to the parts of the loading buckets which are most subjected to wear, such as typically the front edge of a loading bucket. It is also previously known to reinforce other parts of loading buckets as well as loading platforms for dumpers and other construction work vehicles.
Teeth for loading bucket, however, add to the weight of the bucket and the corresponding applies to wear material for loading platforms. Because of this, also possible weight of loaded material in the bucket as well as on the loading platform is reduced.
Further, today's bulky bucket teeth results in that higher resistance occurs when penetrating a pile of material to be loaded. The building height of a loading bucket tooth can very well be more than three the times height of the bucket lip itself.
U.S. Pat. No. 6,174,014 describes a liner for a work machine body, wherein gaps are left between interfitting portions to define openings through the liner. The openings cause material ejected across the liner to tumble, thus reducing the abrasive wear. This described liner is complicated and has proved less effective. It is further only possible to use in limited applications.
Aim and Most Important Features of the Invention
The aim of the present invention is to avoid or at least reduce the problems of the background art and to provide a device of the kind indicated above, which makes it possible to achieve a weight reduction as well as an enhanced resistance against wear.
According to the invention these aims are achieved in a device as mentioned above through the features of the characterizing portion of claim 1.
When pieces, in particular smaller parts of rock or other material to be loaded penetrates into and are hooked against edges, protrusions etc. of the grooves at the inside/upside of the details, in particular of the bucket and the loading platform respectively, as well as the bucket teeth, they are given a “rolling” effect against the wear protection structure. The material that comes into contact with the wear protection structure will thereby at least partially roll on the structure. Rolling stones, crushed material, blasted pieces etc. wear less on the wear protection structure and the rest of the bucket than sliding material would do, wherefore the result will be reduced wear.
The transversal cavities in the form of grooves thus imparts rolling of certain parts of the material to be loaded and dumped by edges etc. getting caught in the cavities.
As a result, the wear protection can be made with smaller dimensions and thereby with reduced weight compared to conventional material having the same resistance against wear. Of course, the presence of grooves in the material results in that the wear protection will be lighter, whereby the amount of loaded material can increase and the wear protection be less expensive to produce.
According to the invention it has been realized that in a device according to U.S. Pat. No. 6,174,014, it is likely that after a certain time of use with handling of material of certain size, material pieces get permanently stuck in the gaps, thereby reducing the function, since the edges of the gaps are likely to be covered.
In particular therefore, according to the invention, the grooves are widening against the outer surface of the wear protection structure. Hereby it is achieved that material loosens more easily from the grooves, whereby they are kept free from otherwise more or less permanently clogging material. The edges of the grooves are hereby kept free for more effective function of engagement with passing rock pieces for imparting them the rolling effect.
Another important difference from U.S. Pat. No. 6,174,014 is that in the device according to the invention the entire grooves including the groove walls and bottom are defined by the wear protection structure. This results in a stronger structure with more foreseeable properties.
Said grooves or cavities should form an almost right angle to said general movement direction and the effect is very good when the angle is about 75-90° to said direction.
It is preferred that the grooves are widening against the outer surface of the wear protection structure, and an open angle of between about 70° and about 120° gives a good combination of retention, in order to impart rolling, and strength of the wear protection structure.
The device according to the invention is applicable in respect of different parts, as for example: a tooth of a loading bucket, a tooth of a digging bucket, a wear protection unit for a bucket, a wear protection unit for a loading platform, a loading bucket, a digging bucket, a loading platform of a mining or construction machine.